Safety Relief Valve Product Literature & Maintenance Guidelines Revision Jun 2008

Transcription

1 Product Literature & Maintenance Guidelines Revision Jun Internal Pressure Relief (Safety) Valves psi Carbon and Stainless Low-Flow psi Carbon High-Flow psi Carbon High-Flow General Warnings and Disclosures: SRV Installation: SRV Operation: Low Flow SRV Disassembly High Flow SRV Disassembly SRV Component Inspection SRV Assembly SRV Testing...13 A... O-Rings for Repairs...14 Drawing No. SRV-IOM 1 Revision: Jun 2007

2 1.0 Internal Pressure Relief (Safety) Valves 1.1 Safety Valves are used to protect the tank from over-pressure in such events as an accident involving a fire. McKenzie Valve supplies both low-flow and high-flow capacity designs generally used for non-insulated non-pressure tank cars. The valve is available with either a 75 psi or a 165 psi start-to-discharge pressure. 1.2 The low-flow valve mounts on a standard 3-1/2 nozzle using (4) 3/4"-10 bolts on a 6-1/4 bolt circle as prescribed by AAR Fig E-21. The valves are constructed of either carbon steel or stainless steel with a stainless trim. 1.3 The high-flow valve mounts on a standard 6-1/2 nozzle using (8) 5/8-11 bolts on a 10-1/4 bolt circle as prescribed by AAR Fig E-11. The valve is constructed of carbon steel with a stainless steel trim. Carbon steel components are fully plated for maximum corrosion protection. 1.4 The safety valves are available with the standard O-ring material options that are color coded and available at the base price. Alternate O-ring materials are also available as a special order. They will be supplied black unless otherwise specified. DESCRIPTION PRESSURE SETTING 75 psi CS SRV 75 psi 75 psi SS SRV 75 psi 75 psi High Flow Safety Valve 165 psi High Flow Safety Valve 75 psi 165 psi (O-RING MATERIAL)** VITON "A" BUNA "N" EPDM NEOPRENE FOOD GRADE SPRING BROWN BLACK PURPLE WHITE A228 MW A SS Powder coated Zinc plated AAR APPROVAL FLOW RATING CAPACITY (SCFM)* SRD SRD PRD PRESSURE (PSIG) SRD *SCFM = Cubic Feet Per Minute of Air at Standard Conditions **See the website or Sales Literature for a more complete listing. 85 Table 1 Standard offerings Drawing No. SRV-IOM 2 Revision: Jun 2007

3 75 psi Carbon and Stainless Low-Flow ( and ) SS SRV CS SRV SS SRV CS SRV SYM DESCRIPTION MATERIAL PART NO REQ 1 GUIDE TOP CAST SS CAST CS BUSHING TEFLON CAP SS CS STEM SS / 6 O-RING / O-RING 1 / 1 used in and VITON B / used in and used in and VITON EXTREME ETP VITON GF-S / / used in and CS / used in and CS4273B / used in and VITON GFLT / used in and NEOPRENE FOOD GRADE / used in and EPDM / used in and BUNA-N / used in and VITON A / FOLLOWER SPRING CAST SS CAST CS O-RING BUNA "N" SAFETY VALVE FLANGE SS CS SPRING SS CS MW NUT, HEAVY HEX, 5/8-11 UNC-2B S.F. W/HOLES A194 GR 6F STUD 1/2-13 UNC -2A x 2 1/8 LG A A193 B NUT, LOCK 5/8 HEX ESNA STEEL PLATED NUT, HEAVY HEX, 5/8-11 UNC-2B S.F. A194 GR 6F NUT, HEAVY HEX, 1/2-13 UNC-2B S.F. A194 GR 6F A194 GR 2H IDENTIFICATION PLATE SS 1 18 SEAL WIRE & DISC SS & LEAD SIZE #2 RD HD DRIVE SCREW SS Table 2 Low-Flow 75 psi Components Drawing No. SRV-IOM 3 Revision: Jun 2007

4 75 psi Carbon High-Flow ( ) SYM DESCRIPTION MATERIAL PART NO REQ 1 SCREW, CAP, HEX HEAD 3/8-16 UNC-2A J429 GR COVER, SAFETY VALVE STEM ALUMINUM SAFETY WIRE 302 SS SCREW, CAP, HEX HEAD 1/2-13 UNC-2A J429 GR WASHER, LOCK 1/2" EXTERNAL TOOTH CS NOZZLE, DISCHARGE A PLATE, LABEL SS 1 9 SIZE #2 RD HD DRIVE SCREW SS FLANGE, BODY A SPRING A RETAINER, SPRING A NUT, HEAVY HEX, 3/4-10 UNC-2B A194 GR2H LOCKNUT, HEAVY HEX, 3/4-10 UNC-2B A194 GR2H SUPPORT, S/A BEARING VALVE, POPPET AND STEM S/A O-RING 1 used in VITON EXTREME ETP used in VITON GF-S used in CS used in CS4273B used in VITON GFLT used in CHEMRAZ used in VITON B used in CERT VITON A used in KALREZ used in CERT VITON B used in KALREZ used in EPDM used in BUTYL RUBBER used in VITON A used in NEOPRENE used in BUNA-N SCREW, CAP 5/16-18 UNC-2A SAE WASHER 11/16 BUNA N CAP POPPET AISI C SEAL LEAD Table 3 High-Flow 75 psi Components Drawing No. SRV-IOM 4 Revision: Jun 2007

5 165 psi Carbon High-Flow ( ) SYM DESCRIPTION MATERIAL PART NO REQ 1 SCREW, CAP, HEX HEAD 3/8-16 UNC-2A J429 GR COVER, SAFETY VALVE STEM ALUMINUM SAFETY WIRE 302 SS SCREW, CAP, HEX HEAD 1/2-13 UNC-2A J429 GR WASHER, LOCK 1/2" EXTERNAL TOOTH CS NOZZLE, DISCHARGE A ADAPTER RING A519 GR PLATE, LABEL SS 1 9 SIZE #2 RD HD DRIVE SCREW SS FLANGE, BODY A SPRING A RETAINER, SPRING A NUT, HEAVY HEX, 3/4-10 UNC-2B A194 GR2H LOCKNUT, HEAVY HEX, 3/4-10 UNC-2B A194 GR2H SUPPORT, S/A BEARING VALVE, POPPET AND STEM S/A O-RING 1 used in VITON EXTREME ETP used in VITON GF-S used in CS used in CS4273B used in VITON GFLT used in CHEMRAZ used in KALREZ used in VITON B used in KALREZ used in FG NEOPRENE used in EPDM used in BUNA-N used in VITON A SCREW, CAP 5/16-18 UNC-2A SAE WASHER 11/16 BUNA N CAP POPPET AISI C SEAL LEAD Table 4 High-Flow 165 psi Components Drawing No. SRV-IOM 5 Revision: Jun 2007

6 2.0 General Warnings and Disclosures: 2.1 The following guidelines describe McKenzie Valve and Machining Company s standard disassembly and reassembly instructions. These are not meant to conflict, override, supersede or be used in place of a company s safety, production, and engineering standards or government rules and regulations. All DOT, AAR, CTC, national, federal, local, and other regulations that apply must be followed. 2.2 Only trained, qualified personnel should perform any procedures described within this brochure. 2.3 Read and understand the entire procedure before attempting any service or inspection. 2.4 These valves are used in numerous services and complete information about the commodity should be obtained, verified, and reviewed before any inspection or maintenance is performed. 2.5 To avoid exposure to toxic or hazardous conditions and materials, ensure that the direct area and all components are free of hazardous materials before performing any maintenance. During maintenance, use appropriate personal protection equipment based on the service in which the valve was used. Residual materials may still be in the valve, so appropriate precautions need to be taken. During installation, take care to ensure the valve is in purchased condition; clean, free of debris, and free of scratches that can lead to leakage. Use appropriate gaskets, fasteners, torque, tools, and methods to install the valve. 2.6 To avoid physical harm, use appropriate equipment to handle the valves. The design of s (SRV) utilizes a compressed spring. These springs store potential energy that could be harmful if uncontrollably released. When transporting, removing, disassembling, assembling, or installing the valves, do not place any part of your body directly in front of the spring. Handle the valves with care to avoid damage to the valve and any of its components which might lead to a discharge of this energy. Never try to manually actuate the valve. Drawing No. SRV-IOM 6 Revision: Jun 2007

7 3.0 SRV Installation: 3.1 McKenzie Valves are designed using standard mounting dimensions from the Association of American Railroads (AAR) Manual of Standards and Recommended Practices, Section C-III, Safety and Operations Specifications for Tank Cars. 3.2 All new valves are set and tested at the McKenzie facility to ensure the quality of the valve. If the valve has remained in its original condition and is not more than six month old, the valve will not require new calibration or testing. Prior to installation, the valve should be handled appropriately and inspected to ensure that the gasket sealing surfaces are clean and undamaged. If the valve is more than six months old or damage is found, the valve will require maintenance. 3.3 As each manufacturer may impose different requirements based on service and design, install the valve using the tank car manufacturer s, or other end user s, specified materials and procedures. 3.4 The valve is designed to be installed with the spring inside the tank. Inspect the sealing surfaces and position the appropriate gasket between the valve and its mounting surface. Carefully lower the valve into position taking care to align the gasket, valve, and mounting surface. 3.5 Check to ensure that the fastener threads are clean. As the fasteners are installed, they should be equally tightened in increments to ensure proper alignment and even gasket compression. As a general rule, the increments should be hand tight, then one third of required torque, then two-thirds, then the complete torque. The fasteners should not be tightened in a circular, or rotational, pattern as this may distort the gasket and result in uneven sealing. A criss-cross, or star, pattern should be used. Once the fasteners are fully tightened, a circular pattern can be used to check the torques After the valve is installed, check for leakage around the newly installed gasket. If any leaks are detected, the valve should be removed, the valve and mounting surfaces should be inspected, and a new gasket must be installed. 4.0 SRV Operation: 4.1 The SRV is not meant to be manually operated. This valve is under spring force and is designed to operate when it is installed into a larger tank or container that experiences a pressure above the valve s rating. Do not attempt to manually actuate the valve, as side loading may occur which in turn may damage the valve. Drawing No. SRV-IOM 7 Revision: Jun 2007

8 5.0 Low Flow SRV Disassembly: (refer to Table 2 and accompanying figures) 5.1 Read and understand the entire procedure before attempting any service or inspection. Follow all safety procedures applicable. 5.2 Before disassembling the valve, measure the assembled height of the spring in the valve. This measurement will be used when assembling the valve. 5.3 Remove the seal disc and seal wire (18). If these are broken, note should be taken that the valve may have been adjusted and spring height may not be accurate. 5.4 Remove the fasteners (16) from the top guide (1) and remove the top guide. Application of a drop of oil to each of the bolts will help when loosening the fasteners. 5.5 Remove the jam nut (12) from the stem of the valve. 5.6 Measure the location of the adjusting nut on the stem. This measurement will be used when inspecting the concentricity of the stem. 5.7 Put the valve upside-down in a spring compression fixture. Apply just enough force to slightly compress the spring. The adjusting nut (15) should move easily. A light amount of oil may be required on the threads. If the valve is stainless steel, anti-seize may be used. 5.8 Carefully remove the adjusting nut (15). 5.9 Slowly and carefully release the force on the spring (10) Remove the spring retainer (7) and the spring (10) from the valve Carefully remove the stem assembly (4) from the valve body (9) Loosen the lock nut (14) holding the o-ring cap (3) on the stem (4) Remove the cap (3) Remove all seal materials (5, 6, 8) from the cap (3) and stem (4). A tool such as an o-ring pick may be needed. Avoid scratching or damaging any sealing surfaces Immediately, discard all seal materials (5, 6, 8). Drawing No. SRV-IOM 8 Revision: Jun 2007

9 6.0 High Flow SRV Disassembly: (refer to Table 3 & 4 and accompanying figures) 6.1 Read and understand the entire procedure before attempting any service or inspection. Follow all safety procedures applicable. 6.2 Before disassembling the valve, measure the assembled height of the spring in the valve. This measurement will be used when assembling the valve. 6.3 Remove the seal disc and seal wire (3, 21). If these are broken, note should be taken that the valve may have been adjusted and spring height may not be accurate. 6.4 Remove the screw (1) and cover (2) from the top of the stem (16) 6.5 Remove the fasteners (4, 5) from the top guide (15) and remove the top guide. Application of a drop of oil to each of the bolts will help when loosening the fasteners. 6.6 Remove the jam nut (14) from the stem of the valve. 6.7 Measure the location of the adjusting nut on the stem. This measurement will be used when inspecting the concentricity of the stem. 6.8 Put the valve upside-down in a spring compression fixture. Apply just enough force to slightly compress the spring. The adjusting nut (13) should move easily. A light amount of oil may be required on the threads. If the valve is stainless steel, anti-seize may be used. 6.9 Carefully remove the adjusting nut (13) Slowly and carefully release the force on the spring (11) Remove the spring retainer (12) and the spring (11) from the valve Carefully remove the stem assembly (16) from the valve body (10) Loosen the cap screws (18) holding the o-ring cap (20) on the stem (16) Remove the cap (20) Remove all seal materials (17) from the cap (20) and stem (16). A tool such as an o-ring pick may be needed. Avoid scratching or damaging any sealing surfaces Immediately, discard all seal materials (17). Drawing No. SRV-IOM 9 Revision: Jun 2007

10 7.0 SRV Component Inspection: 7.1 When a SRV is removed from an existing application, it must be cleaned and inspected. 7.2 All gasket materials must be removed and discarded. While removing the gasket, do not use any tools that may cause scratches or grooves. Ensure that all existing gasket material is removed. 7.3 Inspect the sealing surfaces. For a flat face flange, inspect for scratches that can be detected by sliding a fingernail across. For tongue and groove surfaces, examine the sides of the tongue and groove, as well at the top of tongue and bottom of groove. These surfaces should be inspected for scratches as well as roll over material on the edges. If the tongue and groove dimensions have been distorted by shearing or warping, the joint may not properly align. Any pitting or irregularities, which can be seen or felt, may be cause for rejecting the part. 7.4 Replace the Cap, Body, and Stem/Plug as necessary. Do not attempt to remachine any sealing surfaces. 7.5 Clean all threads where oil was applied during disassembly. These may include top guide fasteners, adjusting nut threads on the stem, the lock nut threads on the stem, and cap screws that hold the o-ring cap. 7.6 Clean and inspect the body of the valve. 7.7 Inspect the bowl area for any corrosion and clean with a Scotch-Brite pad (or equivalent) or 400 grit emery cloth as needed. Bead blasting is an acceptable alternative. 7.8 Inspect the sealing area of the flange with a straight edge to verify that the area by the bolt holes is not bent. Inspect the bolt holes for any damage. 7.9 Inspect all threaded holes and chase with a tap as needed Inspect all mating surfaces between valve parts for corrosion, alignment, etc. Clean as needed with a Scotch-Brite pad (or equivalent). 1. Stem and cap (or stem, retainer and plug) 2. Top guide and body 3. Stem, top guide and body 4. Spring and body 5. Spring and retainer (or spring, follower and guide) 6. Seal retainer and body 7.11 Inspect Stem 1. Wire brush the entire length of stem to remove scale, solidified product and any foreign matter. 2. Visually inspect stem for defects and overall condition including threads and poppet for cracks, nicks, and/or pits caused by corrosion, etc., before continuing. Repair work is limited to cleaning and polishing. 3. If the visual inspection is acceptable, perform a waterwashable liquid penetrant inspection, on the complete stem. Stems with crack like indications shall be replaced. 4. If the threads are slightly galled, run the correct size thread die over the affected area. Stems with severely galled area of thread shall be replaced. Drawing No. SRV-IOM 10 Revision: Jun 2007

11 5. Perform stem concentricity inspection. Equipment needed: 1) Dial indicator on a stand 2) Two v-blocks 3) End stop Procedure 1) Place the top guide end of the stem in one v-block. 2) Place the other v-block at the location where the adjusting nut was measured before disassembly. 3) Place the dial indicator (as shown) on the outer edge of stem (poppet). 4) Rotate the stem ) Observe the total dial indicator movement (maximum to minimum measurement), which will be the T.I.R. (total indicator reading). 6) The maximum T.I.R. shall be: inches for the and designs inches for the and designs 7.12 Inspect Spring 1. Wire brush the entire length of non-coated springs, as needed, to remove scale, solidified product and any other foreign matter. 2. Visually inspect the spring for damage or cracks. A crack in the spring is cause for rejection. 3. If visual inspection is acceptable perform a water-washable liquid penetrant inspection on the complete spring. Springs with crack like indications shall be replaced Visually inspect the follower for damage. Move the follower up and down the length of the stem and guide tube (if applicable). Ensure free movement of the follower. Drawing No. SRV-IOM 11 Revision: Jun 2007

12 8.0 SRV Assembly: 8.1 Inspect all components and ensure they are clean, free of nicks and scratches and are in proper condition for assembly. 8.2 Select the o-ring material per customer s requirements. Clean and inspect the oring(s) and then apply a very thin film of food grade silicone sealant compound to the o-ring(s). 8.3 Insert the o-ring(s) into the cap. 8.4 Press the cap and o-ring(s) into position on the stem. 8.5 Depending on the style of valve, either tighten the locknut or cap screws that hold the cap onto the stem. 1. Locknuts should be torqued to 80 ft-lbs. 2. Cap screws should be torqued to 175 in-lbs, using a criss-cross (star) pattern. 8.6 Place the stem assembly into a fixture with the threaded side up. Apply anti-seize compound on the threads of stainless steel stems. 8.7 Set the valve body assembly onto the stem assembly in the fixture. Insure that the valve body assembly is centered on the stem assembly and is supported squarely on the o- ring(s). 8.8 Place the spring and spring retainer over the stem. 8.9 Compress the spring until the adjusting nut can be started. Tighten the adjusting nut until the measured assembly height (from disassembly) is reached. If a compression fixture is available, compress the spring until the measured assembly height is reached and tighten the adjusting nut Remove the valve from the assembly fixture Install the top guide assembly and fasteners. The stem should not bind on the bushing in the top guide. If it binds, check the alignment of the stem assembly to the valve body assembly. 1. Hex Nuts should be torqued to 75 ft-lbs 2. Hex Head Capscrews should be torqued to 300 in-lbs Drawing No. SRV-IOM 12 Revision: Jun 2007

13 9.0 SRV Testing: 9.1 Install the pressure relief valve in the test well or equivalent fixture. 9.2 Cycle the valve by increasing the test well pressure until there is an audible release of air through the valve, and then reduce the pressure until the air flow stops. Cycling the valve helps provide consistency in test results between valves that have sat for varying lengths of time. 9.3 Plug the drain holes in the valve body (with putty, ear plugs, etc.) and fill the nozzle with water so the cap is covered. 9.4 Start-to-Discharge Pressure 1. The AAR definition of start to discharge pressure (STD) is "the pressure, measured at the valve inlet, at which there is a measurable lift of the closure device on a safety relief valve, or at which discharge becomes continuous as determined by seeing, feeling or hearing." 2. An effective indication of start to discharge pressure is when there is always a bubble of air rising in the water. A single bubble or intermittent bubbles do not constitute a start to discharge. 3. Slowly increase the pressure in the test well. 4. Measure and record the start to discharge pressure as defined above. The acceptable start to discharge pressure is defined in BOE The tolerance for a reclosing pressure relief valve is ±3 psi for valves with a start-to-discharge pressure of 100 psi or less and ±3% for valves with a start-to-discharge pressure greater than 100 psi. If the start to discharge pressure is outside the acceptable range the valve setting should be readjusted by tightening or loosening the spring retaining nut as needed. 9.5 Vapor-Tight Pressure 1. The AAR definition of vapor tight pressure (VTP) is "the pressure, measured at the valve inlet after closing, at which no further fluid flow s detected at the downstream side of the seat of a safety relief valve." 2. An effective indication of vapor tight pressure is when there are no more bubbles or at least a 10 second delay between bubbles. 3. Slowly decrease the pressure in the test well. 4. Measure and record the vapor tight pressure as defined above. The acceptable vapor tight pressure is defined in BOE The vapor tight pressure of a reclosing pressure relief valve must be at least 80 percent of the start-to-discharge pressure. If the vapor tight pressure is below the minimum VTP the valve shall be rejected. The valve should be disassembled and all sealing surfaces closely checked before rebuilding. 9.6 Record the valve serial number, start to discharge pressure, and vapor tight pressure using the AAR certificate of test form, which must be signed and dated. 9.7 Remove the putty, etc from the drain holes and drain off any water. Remove the valve from the pressure test well. 9.8 Install the locking nut (or top nut) by using 2 wrenches to tighten it to 45±15 ft-lbs. against the adjusting nut (or adjusting screw), without changing the adjusting nut position. 9.9 Install the safety wire(s) and lead seal(s) as required. Typical seal locations are: holes in the adjusting nuts, top guide fasteners, set screw, etc. Drawing No. SRV-IOM 13 Revision: Jun 2007

14 Appendix A : O-Rings For and Low Flow 75 psi SRV/PRV SYM #5 SYM #6 SYM #8 BUNA-N BUTYL RUBBER CS 4273B CS EPDM KALREZ NEOPRENE NEOPRENE FOOD GRADE VITON A VITON B VITON EXTREME ETP VITON GFLT VITON GF-S CHEMRAZ For and High Flow SRV/PRV SYM #17 BUNA-N BUTYL RUBBER CHEMRAZ CHLOROBUTYL CS 4273B CS EPDM KALREZ KALREZ NEOPRENE FOOD GRADE VITON A VITON A - CERTIFIED VITON B VITON EXTREME ETP VITON GFLT VITON GF-S Drawing No. SRV-IOM 14 Revision: Jun 2007